What is PEX? Plus Tips for Using PEX

Everything you
always wanted
to know but
were afraid
to ask

PEX tubing and fittings are starting to push copper out of home-handyman (and plumbers') toolboxes. Learn tips for working with it and what all the specialized tools and fittings are for in this article.

By the DIY experts of The Family Handyman Magazine:February 2010

Overview

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PEX advantages

PEX costs less
than half the price
of copper and
installs much
faster. And since
it's flexible, PEX
makes remodeling
jobs easier.

I’m not a plumber. But like any
remodeler, I occasionally find
myself relocating a hose bib or
fixing a pipe that managed to get in the way of my
Sawzall. For years, my plumbing kit was a torch and a
bucket of copper fittings. These days, that bucket mostly
holds PEX fittings and tools. And my soldering torch
doesn’t get used much anymore.

Switching to PEX wasn’t difficult; PEX is a whole lot
easier to master than copper. The only tricky part was
deciding what to carry in my plumbing bucket. Visiting
the plumbing aisle at my local home center didn’t help
matters—all those strange tools, connection systems and
unfamiliar thingamajigs made my head spin. But with
lots of advice and a little on-the-job training from
plumber friends, I figured out what’s needed and what isn’t. Here’s what I learned about getting set up for PEX.

Choose a common connection system

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Cinch rings

Cinch rings tighten
as you pinch the
tab with the tool.

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How they work

Cinch rings fit over the pipe and tighten just enough to make the connection with the barbed fitting watertight.

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Crimp rings

Crimp ring connections
are made by
compressing a copper
ring around the PEX
and fitting.

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How they work

Crimp rings compress slightly to seal the PEX.

Before you choose a system for connecting PEX to fittings,
check what’s available at the stores where you like to shop.
There are a half-dozen systems out there, but most are available
only through specialty plumbing suppliers. If you want to shop
at home centers and hardware stores, there are two widely
available methods to choose from: copper crimp rings and
stainless steel cinch rings. I like the cinch system better
because the tool is smaller and one tool can handle
four ring sizes (3/8 to 1 in.). But cinch rings aren’t as widely
available in my area, so I chose the crimp system instead.
Crimp rings require a different tool for each size or a combination tool, and the bigger
tools are awkward in tight spots. Still, I’d rather put up with the
drawbacks of the crimp system than drive across town to get
supplies. You can also shop online. Whatever system you choose, keep an
eye on prices: I’ve found that the costs vary a lot from
one supplier to another.

Buy sticks, not coils

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Coils vs. sticks

Coils are great
when you have lots
of long runs, but
straight "sticks"
are a lot easier to
work with. The red
and blue colors
eliminate hot-and-cold
confusion.

PEX has a strong “memory”; it always wants
to spring back to its original shape. So
working with a coil of PEX is like wrestling with a
giant Slinky. For most jobs, you’re better off buying
10-ft. “sticks” instead. You may have to pay a few cents more
per foot and install a coupler or two, but you’ll
avoid frustration and kinks. Even plumbers who
run miles of PEX every year often buy sticks rather than coils.

Stock up on push-ins

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Versatile fittings

Push-in fittings work with
copper and CPVC as well
as with PEX.

Don’t show up on any PEX job without a few
push-in elbows, tees and couplings
(SharkBite is one brand; www.sharkbite.com). They’re
the best solution for cramped quarters where
there’s no space for a crimping or cinching tool.
No tool is needed; just push in the PEX and walk
away. And since they also work with copper and
CPVC, you can carry just a few push-in fittings
rather than a huge collection of special transition
fittings. Convenience doesn’t come
cheap, though. You’ll spend from $5 to $12
per fitting. Also, check with your local
inspector before you use push-in fittings.
Some jurisdictions don’t
allow them in inaccessible
locations like inside walls.

Bend PEX carefully—or not at all

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Avoid kinks

A bend sleeve prevents kinking
or creating a too-tight bend.

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Bend sleeve

Bend sleeves are inexpensive accessories sold wherever PEX is sold.

PEX is easy to kink. With one brand
(Uponor Wirsbo), you can restore
the tubing by heating it. But with most
PEX, you have to cut out the kink and
splice in a new section. You can also
damage PEX by overbending it. (The
minimum bend radius is typically six to
eight times the outer diameter,
depending on the manufacturer.) One
way to avoid kinking and overbending
is to use bend sleeves. Keep in
mind that—even with a sleeve—a bend
requires open working space. In tight
situations, save yourself some struggling
by using an elbow fitting instead.

Get a crimp cutter

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Crimp cutter tool

A crimp cutter lets you
remove crimp rings without
damaging the fitting.

PEX fittings cost about three times as much as
copper fittings. So you won’t want to toss your
mistakes in the trash. If you use cinch rings, you can
saw or twist off the ring tab, pull off the PEX and reuse
the fitting. But sawing through a crimp
ring—without damaging the
fitting—is a job for a surgeon.
For the rest of us, a
crimp cutter is a
lifesaver. Just slice off
the PEX flush with
the fitting and make
two cuts in the ring.

Stub out with copper

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Stub outs

Copper stub-outs provide a PEX connection on one end
and solid support for shutoff valves on the other.

You can buy shutoff valves that connect directly to PEX.
But don’t. PEX can’t handle abuse the way copper
can—picture a homeowner cramming more and more stuff
into a vanity or cranking that crusty valve closed years from
now. So use copper rather than PEX for wall stub-outs. For
risers coming out of the floor (or extending down from the
ceiling to a laundry tub faucet), use lengths of copper pipe.

Tools & Materials List

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

Utility knife

You'll need either a cinch tool or a crimp tool, as well as a crimp cutter.

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.